Conversion of hydrocarbons



Patented Apr. 8-, 1941 7 2,237,222 conversion or maooaanons Edwin T.'Layng, Jersey City, N. 1., asslgnor to The Polymerization Process C rn ration, Jersey City, N. 1., a corporation of Delaware No Drawing.

Application November a, 1939, Serial No. 303,541

a claims. (CL- me-ioi This invention relates to the conversion of oiefinic hydrocarbons to hydrocarbons of higher boiling points. More particularly, the invention relates to a process for the conversion of lowiling normally gaseous and normally liquid hydrocarbons to hydrocarbons within the motoriuel boiling range.

It has been suggested previously to eflect polyerization or oleflnic hydrocarbons under suit able conditions by means of various catalytic materiais. connection with the presefit ipvention it has it discovered that acid pyrophosphates. of cermetals are highly eifective as catalytic contact agents for promoting the polymerization of oleiinic hydrocarbons. These acid pyrophos phates are: CuIhPzO'z. HgHaPsO'l. ZnHzPaOr. gHaPzOw. FeaI-IatPzOvla, v AhHdPzO-m and @oHsPa-Or. In carrying out the invention the olefinic hydrocarbons, or hydrocarbons containing oleflnicconstituents, are passed in contact with the cataiytlc contact agent in a suitable reactor, the hydrocarbons being preheated suitably for the rection. Any suitable pressure may be used. but

the. operating temperature and the space velocity of the charge. Many combinations of these variables may be used in obtaining the desired amount and quality of production, but by reference to the following general description and specific example it will be possible to select weight conditions and produce a desired result without undue experimentation.

The metal acid pyrophosphates employed in the present invention may be prepared advantageously by the reaction of a soluble salt of the desired metal with a soluble metal acid pyrophosphate such as Na-rHzPaO-I. In the following descrlptionof the preparation of the metal acid pyrophosphates reference will be had to the use of sodium acid pyrophosphate or secondary so dium pyrophosphate, by way of example. It will it ispreferable to employ relativelyhigh pressures, for example in excess of 150 pounds per touare inch. I Since the rate of polymerization is a iunction of the concentration of the oleflns such YESSUI'B.

reactions are best operated at superatmospheric The operating temperature will depend some what upon (the nature of the material under treatment and the product desired. For exampie, for the conversion of gaseous olefins, such as butylenes, a temperature of appr im to 400 F. is advantageous for eflecting maximum conversion to gasoline constituents. Generally,

temperatures within the range of 259 to 500 F. will be found to be advantageous for the conversion of low-boiling oleflnic hydrocarbons to'gasoline constituents. v v

The extent of reaction and the character of the liquid product are aifected by the length of reaction time as well as by the reactiontempera- It is apparent that with any given charge the extent of reaction and the character of the product dependmainly upon the operating pressure,

be understood, however, that other soluble acid pyrophosphates such asthat of potassium are equailyvaluable for the p rp se.

Secondary sodium pyrophosphate or dihydrogen" sodium pyrophosphate may be prepared by any suitable method such as by the controlled dehydration of sodium dihydro gen orthophosphate, or; preferably, by reacting equal molar amounts of sodium pyrophosphate and sulphuric acid in the following manner:

The sodium dihydrogen pyr phosphate then can be mixed with a solution of a soluble salt of the desired metal such as copper sulphate to give the desired product in accordance with the following reaction: I

phosphate-sulphuric acid solution was poured Y rapidly into the copper sulphate solution and the whole stirred rapidly. Upon continued stirring a light blue crystalline precipitate was formed. The mixture was then filtered and the filter cake washed several times .by stirring each time with distilled water and refllterins. The washed filter number.

' cake was then dried at 230 F. for 24 hours and pelleted into inch pellets.

The foregoing discussion of the preparation of the catalytic contact material refers, for exam- 2,237,822 treatment of a gas containing as the olefinic conof the metals of the other acid pyrophosphates listed above in the preparation of a the various active metal acid pyrophosphates.

For an example of the use of catalytic contact material thus prepared under specific operating conditions the results obtained from an opera tion'on a butane-butene gas mixture containing 27% normal butene and 10% isobutene may be referred to. In this operation the gas was passed over catalytic contact material consisting of copper dihydrogen pyrophosphate at a rate of 33 to 37 cubic feet, (measured as gas at standard conditions of temperature and pressure), per pound of catalytic contact material per hour. A pressure of 1400 pounds per square inch was maintained on the reactor, and the reactor was brought rapidly to an operating temperature of 400 F. In a test period of over 100 hours duration the liquid polymer yield was approximately 23.2% by weight based on the charge, representing a 62% conversion of the olefins charged.

If more complete conversion of the oleilns had been desired in connection with the operation described above this could have been accomplished by changing one or more of the variables of temperature, pressure and space velocity dis-- cussed previously. For example, it could have been accomplished conveniently by raising the operating temperature slightly. for example, to-

450 F. or by reducing the space velocity slightly or by means of both variations,

As mentioned above, the extent of conversion is effected by the variables of temperature, pressure and space velocity. The character of the liquid product is eflected also by these variables in respect to its boiling point and, in the case of gasoline, in respect to its octane number. For example, it may be desirable to limit the extent 'of conversion obtained in order to obtain a gasoline product of relatively high octane number.

The eii'ect-oLthe extent ofconversion in the octane number is particularly noticeable in connection with the treatment of gaseous mixtures containing both normal butenes and isobutenes. For example, in the treatment of amixture of normal and is'obutenes at a temperature such as that mentioned above it is found that conversion of the isobutene proceeds more rapidly than conversion of the normal butene so that by limit ing the time of contact of the charge with the catalytic contact material it is pomible to eil'ect preferential conversion of the isobutene and thus of relatively high octane obtain a production While the foregoing example refers to the stituents only normal and isobutenes, it is quite apparent that the process is equally applicable to the treatment of other oleiins. For example. a gaseous mixture containing propylene in substantial proportions as well as butenes may be treated with equal facility; or a gas comprising propylene as its principal olefinic constituent may be treated as well. In the treatment of gaseous mixtures including substantial proportions of propylene it may be desirable in order to eflect substantial conversion of propylene to employ a somewhat higher temperature and a somewhat lower feedsrate than the above example. For example, in thetreatment of a propane-propylene gas containing 30% of propylene a feed rate of 10 cubic feet measured as gas at standard conditions oi temperature and pressure per polmd of catalyst per hour and a temperature of 400 to 500 F. are found to be advantageous.

I claim:

1. The method of converting oleilnic hydrocarbons to hydrocarbons of higher boiling points by polymerization thereof which comprises contacting said olefinic hydrocarbons at elevated temperature with a catalytic contact agent comprising as an essential ingredient an acid metal pyrophosphate selected from the group consisting of CllHzPrOr, HgHaPzOv. ZnHzPzOv. MgHsPzOw, FGZH6(P2QJ 3,, AlzHc (P201): and COHzPzOr.

2. The method of claim 1 wherein copper dihydrogen pyrophosphate is employed as said metal acid pyrophosphate,

' 3. The method of treating a mixture of hydrothe gasoline boiling range by polymerization thereof which comprises contacting said mixture of hydrocarbons at elevated temperature with a catalytic contact agent comprising as an essential ingredient a metal acid pyrophosphate selected from the group consisting of CuHzPzOn HgHzPzO'r, ZnHzPzOv, Mgl-IzPaO-i, FezHflPzOrh. A12Hs(P2O'I)3 and COHrPzOr, and limiting the extent of conversion of said hydrocarbons to higher boiling products to obtain a gasoline product of relatively high octane number.

4. The method of claim 3 wherein said mixture of hydrocarbons comprises normal butenes and isobutene.

5. The method of claim 3 wherein copper dihydrogen' pyrophosphate is employed as said metal acid pyrophosphate.

6. The method of converting oleflnic hydrocarbons to hydrocarbons of higher boiling points which comprises contacting said oiefinic hydrocarbons with a metal acid pyrophosphate selected from the group consisting of. CllHaPzOv.

said conversion. EDWIN '1. LAYNG. 

